(Reuters) - A self-described white nationalist who owned assault-style weapons and World War Two Nazi memorabilia has been charged in federal court with making threats to attack an Ohio Jewish community center, for which he already faces state charges, authorities said.

James Reardon Jr., arrested on charges of threatening to attack a local Jewish community center, is shown in a booking photo in Youngstown, Ohio, U.S., provided August 19, 2019. Mahoning County Sherriff's Office/Handout via REUTERS

James Reardon, 20, whose case is one of many thwarted potential mass shootings reported by U.S. law enforcement in recent weeks, faces one count of transmitting threatening communications via interstate commerce, federal prosecutors said as his indictment was unsealed on Thursday.

He is accused of threatening to carry out a gun rampage targeting the Jewish Community Center of Youngstown, Ohio. Federal authorities said their investigation is ongoing.

“The Constitution affords citizens many rights, but it does not allow people to threaten others with violence,” U.S. Attorney for the Northern District of Ohio Justin Herdman said in a statement.

Reardon pleaded not guilty on Aug. 19 to state charges of aggravated menacing and online harassment in connection with the alleged planned attack. His case is scheduled for trial in Struthers Municipal Court on Sept. 13. [nL2N25F0XJ]

Reardon’s attorney did not immediately return a call seeking comment.

The case is one of a recent spike in reported planned shooting attacks, according to the FBI, which said calls to its tip line designed to head off mass attacks surged by 70% since twin massacres earlier this month in El Paso, Texas, and Dayton, Ohio. [nL2N25M0XI]

Reardon, who is being held in the Mahoning County jail on $250,000 bond, had posted a video on social media alluding to an attack on the Jewish center and referring to himself as a white nationalist, U.S. authorities said.

He was arrested on Aug. 16. Investigators who searched his New Middletown home found several firearms, including an MP-40 sub-machine gun and an AR-15 assault-style rifle, as well as numerous Nazi World War Two propaganda posters and a Hitler Youth knife, they said.

Also at Reardon’s home was a video of a National Geographic documentary that showed him attending the August 2017 “Unite the Right” rally in Charlottesville, Virginia, at which a counter-protester was killed, they said.

“Law enforcement must react swiftly to threats of violence,” Special Agent in Charge Eric Smith said in a statement. “This defendant’s video demonstrated that he had access to weapons and he posed a threat to a Jewish community center.”